If you plan to drive with the cover on, ensure it is rated for "road use" or "towable."
I can then find specific that fit your needs. buy boat cover
Never let water pool on the cover. Use adjustable poles to create a "tent" so rain runs off. If you plan to drive with the cover
Measure the widest part of the boat (usually near the middle). buy boat cover
The most popular choice. It is strong, UV-resistant, and doesn't stretch much. Look for "Marine Grade" labels.
What do you have? (e.g., Bass boat, Pontoon, Center Console)